In the development of solar cell applications, dye-sensitized solar cells (DSSCs) have a high potential. A photosensitizer contained in DSSCs absorbs visible light and ultraviolet light in sunlight, and electrons contained in the photosensitizer are thus excited and effectively introduced to a conduction band of a semiconductor electrode so as to produce a photocurrent. Therefore, the quality of the photosensitizer may affect the photoelectric conversion efficiency of DSSCs. The photosensitizer commonly used in DSSC includes ruthenium complexes, porphyrin derivatives, and small molecular organic photosensitizers having electron-donating and electron-withdrawing structures.
US 2003/0203888 A1 discloses a bacteriochlorin chromophore represented by Formula (A):

wherein
X1, X2, X3, and X4 are independently selected from the group consisting of H, OH, halo, a C1-C4 alkyl group, and a C1-C3 alkoxy group; and
P1, P2, P3, P4, P5, Q1, Q2, Q3, Q4, and Q5 are independently selected from the group consisting of H, OH, CN, NO2, halo, a C1-C15 alkyl, and a C1-C15 alkoxy group.
As disclosed in Scheme 1 of US 2003/0203888 A1, a carbon-carbon double bond at β-position of one or two pyrrole rings of a porphyrin compound is reduced using oxmium tetraoxide as a catalyst to produce a chlorin compound and a bacteriochlorin compound. However, the bacteriochlorin compound prepared from the porphyrin compound in US 2003/0203888 A1 has no or only one substituent on each of the carbon atoms at positions 7, 8, 17, and 18 of a multi-cyclic core. In addition, it is indicated in the CRC Handbook of Organic Photochemistry and Photobiology, Volumes 1 & 2 (Second Edition, Sep. 29, 2003) by William M. Horspool et al., Page 144-3 that the bacteriochlorin compound prepared from the porphyrin compound via reduction is found to be air sensitive. The bacteriochlorin compound thus prepared is liable to be oxidized to the porphyrin compound or the chlorin compound, and may not be used for subsequent applications over a long period of time. The bacteriochlorin compound prepared from the porphyrin compound using oxmium tetraoxide as a catalyst, as disclosed in US 2003/0203888 A1, may similarly have the air sensitive problem.
U.S. Pat. No. 7,534,807 discloses a method of making a bacteriochlorin, which is carried out by condensing a pair of compounds of Formula II defined therein in an organic solvent and preferably in the presence of an acid.